Digital flat X-ray detectors have been changing classic radiography or fluoroscopy, angiography and cardanigiography for years. The most varied technologies, including digital ones, have already been in use in part for a long time, examples being image intensifier camera systems based on television or CCD cameras, storage film systems with an integrated or external readout unit, systems with optical coupling of the converter foil to CCDs or CMOS chips, selenium-based detectors with electrostatic readout (for example Thoravision) and solid-state detectors with active readout matrices and direct or indirect conversion of the X-radiation.
In particular, novel solid-state detectors (FD) for digital X-ray imaging have been undergoing introduction to the markets for a few years; these are based on active readout matrices, for example made from amorphous silicon (a-Si). The image information is converted in an X-ray converter, for example caesium iodide (CsI), stored in the photodiodes of the matrix as electric charge, and subsequently read out via an active switch element with the aid of dedicated electronics, subjected to analog-to-digital conversion and processed further by the image system.
Related technologies likewise employ an active readout matrix made from amorphous silicon, but a converter (for example selenium) that directly generates electrical charge that is then stored on an electrode. The stored charge is subsequently read out in order to generate an image signal. Other technologies are based on CCDs (charge coupled devices) or APS (active pixel sensor) or large-area CMOS chips, as described, for example, in Spahn et al., “Röntgen-Flachdetektoren in der Röntgendiagnostik” [“Flat X-ray detectors in X-ray diagnostics”], Radiologe 43 (2003), pages 340 to 350.
Portable flat X-ray detectors have also recently become available. These are used both for free images and for so-called bed lungs. In the technical jargon, bed lungs are pulmonary images taken with the aid of a mobile X-ray diagnostic device in the bed.
Particularly in the case of these bed lungs, but also, however, in the case of other applications, the detector is placed completely below the patient. This may include, for example, a handle that is attached on the longitudinal side of the flat X-ray detector and lies transverse to the bed. Above all else, it is difficult with patients who are older, traumatized or otherwise difficult to move for handling to be carried out below the patient, to place the flat X-ray detector and to remove it. Such a flat X-ray detector having a grip is known, for example, from the brochure by Siemens Medical Solutions entitled “AXIOM Multix M Your portal to the world of direct digital radiography” with order number A91100-M1200-B527-2-7600.